XCSOURCE T-Ring + 1.25 Inch Telescope Mount Adapter + Extension Tube for Nikon DSLR DC619 Prime Focus Photography - Use direct with your camera. Simple Barlow Projection - Use above with your barlow and camera. Eyepiece Projection - Use your eyepiece in extension tube. Extended Barlow Projection - Use extension tube with your barlow (Extended barlow projection makes a 2x barlow into a 3x or more barlow). High Quality and Brand New.